(1) Field of the Invention
The present invention pertains to an aerial refueling system for unmanned aircraft. More specifically, the present invention pertains to an apparatus and method for refueling an unmanned aircraft in-flight. The apparatus is responsive to sensed forces acting on a refueling receptacle of the aircraft by a separate refueling probe, to control movements of the aircraft as it is being refueled to reduce the magnitude of the sensed forces and thereby maintain the coupling of the aircraft with the refueling probe.
(2) Description of the Related Art
Aerial refueling systems have been used in aircraft for many years. The systems find extensive use in military aircraft to extend the travel range and flight time of the aircraft. A typical refueling system employs a receptacle on the exterior of the receiving aircraft that is designed to receive and couple with a refueling probe of a fuel supplying aircraft.
In the operation of a typical aircraft refueling system, the refueling probe of the fuel supplying aircraft is extended to a position that is displaced a sufficient distance from the aircraft to enable a receiving aircraft to safely approach and couple with the extended probe. The receiving aircraft has a refueling receptacle on its exterior. The pilot of the receiving aircraft maneuvers the aircraft into a position where the distal end of the supplying aircraft refueling probe will be received in the refueling receptacle of the receiving aircraft.
In known in-flight refueling systems, the distal end of the refueling probe is typically coupled to the receiving aircraft when the probe distal end is received in the receiving aircraft refueling receptacle. The coupling between the refueling probe and the receiving aircraft refueling receptacle enables fuel to be safely transferred from the fuel supplying aircraft to the receiving aircraft. However, the coupling between the supplying aircraft refueling probe and the receiving aircraft refueling receptacle is not sufficiently strong to keep the receiving aircraft coupled to the supplying aircraft. It is necessary that the pilot of the receiving aircraft maneuver the aircraft and hold the aircraft in a position where the coupling between the supplier aircraft refueling probe and the receiving aircraft refueling receptacle is maintained.
With the growing use of unmanned aircraft in military combat and reconnaissance operations as well as in other operations, it has become desirable to perform in-flight refueling of the unmanned aircraft. With the ability to refuel the unmanned aircraft in-flight, the aircraft can increase its travel range, increase its flight time, and ultimately improve its performance in conducting the mission for which the unmanned aircraft has been chosen. However, unlike refueling operations conducted by manned aircraft where the pilot of the receiving aircraft is capable of maneuvering the aircraft to maintain the coupling with the refueling probe of the fuel supplying aircraft, in-flight refueling of unmanned aircraft presents unique problems. It can be appreciated that the tracking, the capturing or coupling, and maintaining the coupling of a refueling probe with the refueling receptacle of an unmanned aircraft having little or no visual information on the location of the refueling probe relative to the unmanned aircraft can be extremely challenging. To further complicate the desirability of refueling unmanned aircraft, the current existing fleet of supplier tanker aircraft imposes additional design constraints on the in-flight refueling of unmanned aircraft. In particular, any in-flight refueling system for unmanned aircraft requiring modifications or upgrades to the computer control systems of the supplier tanker aircraft may be critiqued as being too costly and/or impractical to implement.